American Heart Association reported that the cardiovascular disease is the largest cause of death and more than 2,600 people die of it every day. Korea also shows the increasing prevalence rate of the disease caused by arteriosclerosis since 1980's when eating habit started to turn westernized.
Percutaneous transluminal coronary angioplasty is a method to treat stenosis when there is serious hemadostenosis after angiocardiography is conducted and it is performed for patients with stroke, angina pectoris, myocardial infarction, etc. It is an invasive treatment through blood vessels. Yet, due to the bypass, the required days for hospital treatment are shorter than those of surgeries and several follow-up operations are possible, showing low death rate. For the treatment, a guidewire is inserted into the coronary artery with lesion and a balloon catheter is put in the lesion part and then expanded by pressure to widen the narrowed lesion. The rupture, crush, and extension of atherosclerotic plaques by the expanded balloon widen the lesion. Yet, it had a disadvantage that it had to be performed several times because side effects occurred by inducing remodeling of vessels, which cause blood vessel injury, and extension of tunica media and resulting in 30˜70% of patients having narrowed lesions back in six months.
Even after repeating this process several times, when there is serious stenosis or a vascular occlusion by vascular dissection and ruptured atherosclerotic plaques, then a stent, a metal mesh, is inserted to prevent it.
Since Benestent and stress clinical research in 1994, which set the ground that stent treatment can have higher restenosis reducing rate than balloon angioplasty, the stent operation has been more common up to 80˜90% in coronary stenosis treatment in current clinics. Even after the stent operation became popularized, 15˜20% of restenosis could not be resolved. Radioactive treatment was employed to overcome it, but its use was limited due to later restenosis and thrombosis. However, to overcome the problem, agent-coated stents were recently developed, reducing the restenosis rate on the stent surface down to less than 10% by using anticancer agents or immunosuppressants (examples of Sirolimus eluting stents are Ravel, Sirius, C- & E- Sirius, Direct, Svelte, Sirius, Reality; examples of Paclitaxel-eluting stents are Taxus I˜VI, Endeavor-I˜III etc.) and their efficiency was proven through the research. Yet, since these agents that coat stents use anticancer agents or immunosuppressants, there is a possibility of toxicity in endotheliocytes.
The percutaneous coronary interventions are performed over 10,000 times a year in Korea, and the domestic market is worth more than 20 million dollars. The stents for angioplasty have been barely domesticated and also all medical materials and agents developed overseas cost a huge amount of national wealth for paying royalty every year. Thus, it is expected that new targets of cardiovascular diseases and the development of new drugs will bring enormous economical and social profits. Since it was reported that the agent-coated stents deliver local agents effectively and continuously and remarkably reduce the restenosis rate within stents, they have been recently on the market in the nation at about twice higher price than the existing stents. Also, the future market of agent-coated stents is expected to grow much faster, so there is a desperate need for their technical development.
On the other hand, the biomaterial agent market is on the rise all over the world now. Among RNA researches, the RNA interference (RNAi) research is greatly in the spotlight, especially small interfering RNA (siRNA) technology, which can induce RNA interference, is getting a lot of attention. Also, siRNA causing RNA interference intercepts gene information for protein synthesis as if it were a gene switch in RNA wire that delivers gene information, so it can be applied in various ways including infectious disease treatment as well as inherited disease treatment.
The most important matter in current RNA interference technology is that there is no siRNA delivery system, so the efficient and safe delivery system that inserts siRNA into target cells is needed to well induce RNA interference effect.